The one you play better. For some it is Type, for other T34, one will easily get 100k in Supershing, other will ragequit after one battle with it and switch to Lowe to earn 100k. It is all matter of personal preferences.

Many will argue due to long standing knowledge that the Lowe and T34 bring in the most, but I have tried almost all the premiums and my Super P brings in just as much if not a higher average then both the Lowe and T34, and at half the cost to get. Its the most bang for the buck teir 8. The SU-144 is great too at tier 7 but only brings in about 1/2 to 3/4 what the Super P does.

totally depends on your play style. i have all of them and i like all of them with the exception of the super pershing. it's just too damn slow. i probably avg more credits with the kv5. i think it's mainly because i enjoy it the most. it's just a fun tank that fits my playstyle well. charging in and bullying other tanks is just fun.

one thing to take into consideration is that all the current tier 8 premiums get favorable match making except the Lowe and the T34. so, if u dont want to be in tier 10 matches with a tier 8, i'd suggest one of the others.

a second thing to consider is which crew u'd like to level. u can put a crew from the same nation and tank type (light, med, heavy, td, arty) into a premium tank and take no penalty on crew skill. so it's a great way to make credits and train your favored crew.